1. Field of The Invention.
The present invention relates to a system and a process for controlling a space-division switching network.
The system and process according to this invention apply to networks having crosspoints which each have four coils switching their respective contacts. In particular, they apply to networks wherein crosspoints are electromagnetically controlled by means of current pulses supplied to the coils and are magnetically held according to a method such as that described in the French patent No. 1,393,336, corresponding to the U.S. Pat. No. 3,524,167.
2. Description of the Prior Art.
In numerous known switching systems, crosspoints include two contacts coupled to speech leads and a control contact which makes it possible to test crosspoint condition and to detect operation faults, if any.
In present systems and, particularly, in sealed contact systems, those faults occur rarely and are all substantially caused by electric failures in control system circuits or by lacks of continuity in connections and crosspoint switching coils.
Thus, crosspoint control contacts may be suppressed to the extent that components possibly affected by failures are controlled. In large-size central control space-division switching systems, the use of two-contact crosspoints results in important volume and cost savings.
Implementation of large size networks obviously is very expensive due to the number of utilized components. For reasons having to do with cost reduction and control, it as apparent to be of great interest to find an arrangement permitting a reduction in the number of items by using common items, which as a consequence reduces to the same extent the number of test items and makes possible more careful and systematic control.